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16 June 2003 AGE-NC Project No. 03-1042 Page 2 of 5 20,000 feet in the south central portion of the valley. The sedimentary formations range in age from Jurassic to Recent,with the older deposits being primarily marine in origin and the younger deposits being primarily continental. Continental-derived sediments were primarily deposited in lacustrine, fluvial,and alluvial environments with sediment sources being the mountain ranges surrounding the valley(Olmsted and Davis, 1961);the site itself is located on unconsolidated and semi-consolidated alluvium, lake, playa and terrace deposits of Quaternary age (California Division of Mines and , Geology, 1977).Rocks composing the basement complex of the Province have not been completely defined but are believed to be metamorphic and igneous in origin. The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground Water Basin(Basin 5-22). The estimated depth to ground water at the site is approximately 40 to 50 feet below surface grade(bsg)based on information from Lines of Equal Depth of Water Wells Fall 1999,published by the San Joaquin County Flood Control District and Water Conservation District- FCD&WCD. Based on the map titled Lines of Equal Elevation of Groundwater Spring 1999 also published by the San Joaquin County FCD&WCD, the local ground water elevation is generally toward the east. However, this may be greatly modified by local recharge and discharge patterns. 2.2. POTENTIAL SOURCES OF CONTAMINATION The previous Phase I site assessment revealed several potential sources of contamination due to prior uses of the property: • Contamination to the subsurface from the service pit or vault associated with the in-ground scale located near the northwest corner of Parcel 08. • Contamination from a former diesel AST and associated fueling system known to be in-place on the property for three to five years and removed in 1993.The possible location of the AST was noted on Parcel 19 during the site reconnaissance. • The long term use of Parcel 08 as a canning facility and the denotation on the 1950 and 1972 Sanborn Fire Insurance maps that the property used fuel oil,possibly in the location of the former boiler room. 3.0 SCOPE OF WORK AGE proposes to collect soil samples to determine if petroleum hydrocarbon-impacted soil and/or ground water is present beneath the site. The Phase 11 site assessment will include the following tasks: